Electrochemical properties of the ball-milled LaMgioNi_(2-x)Al_v alloys with Ni powders (x = 0, 0.5, 1 and 1.5)

摘要

The structure and electrochemical hydrogen storage properties of the ball-milled LaMgioNi2 alloys with Ni powder in the range of 50, 100 and 150 wt. percent, respectively, were investigated. It was found that the amount of Ni addition was a key factor influencing the electrochemical properties. The amorphous (LaMg_(10)Ni_2 + 150 wt.percent Ni) composite exhibited a high discharge capacity of 832m Ah/g. The effect of partial substituted Al for Ni in the LaMg_(10)Ni_2 alloys on the electrochemical properties was also studied. The experimental results showed that the amorphous-like (LaMg_(10)NiAl +150 wt. percent Ni) composite exhibited the highest discharge capacity of 953 m Ah/g, corresponding to a hydrogen storage capacity of 3.56 wt.percent. The Al substitution for Ni in the LaMg_(10)Ni_2 alloys had a positive effect on the hydrogen storage capacity. But, the cycling stability needs to be improved when they are to be considered as electrode materials. The reason why the ball-milled (LaMg_(10)MAl + 150 wt.percent Ni) composite had the highest hydrogen storage capacity was analyzed by powder X-ray diffraction (XRD) and electrochemical impedance spectra (EIS). The existence of a second phase (AlNi) in the LaMg_(10)NiAl alloy probably plays an important role in the improvement of the catalytic activity and the electrochemical properties.